13-6 How Can We Use Water More Sustainably? Concept 13-6 We can use water more sustainably by cutting water waste, raising water prices, slowing population growth, and protecting aquifers, forests, and other ecosystems that store and release water.

Reducing Water Waste Has Many Benefits Cutting the waste of water is almost always ___________ and ___________ costly than trying to provide new supplies Three important stats concerning water waste Almost _______________ of water used worldwide is wasted through evaporation, leaks, and other losses In the U.S. – the world’s ___________________ user of water – about __________ is unnecessarily wasted It is economically and technically feasible to reduce water waste to _______ - which would allow us to meet all of our water needs quicker less two-thirds largest half 15%

Reducing Water Waste Has Many Benefits According to water resource experts, the first major cause of water waste is water’s ______________ to users. Result of government ___________________ provided to farmers so that they can use water at below-market prices The second major cause of water waste is a lack of government subsidies for _________________ the efficiency of water use. A basic rule of economics is that you get more of what you reward low cost subsidies improving

We Can Cut Water Waste in Irrigation About ______ of the irrigation water supplied throughout the world does not reach the targeted crops ______________ irrigation Water obtained from a well or surface water flows by gravity through unlined ditches to crops Loses 40% of the water through evaporation, seepage, and runoff _______________ main irrigation system Gravity flow (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river. 60% Flood China’s

We Can Cut Water Waste in Irrigation ________________________ irrigation…(low pressure sprinkler) Uses pumps to spray water on a crop _____ of water reaches crops Low energy _______________ application sprinklers ______________ _____________ of water reaches crop Center pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Center Pivot 80% precision LEPA 90-95%

We Can Cut Water Waste in Irrigation _________ or trickle irrigation (microirrigation) Uses perforated plastic tubing to deliver drops of water at a slow and steady rate near the plant roots ___________ efficiency rate _______________ - so it is only used on about ______ of our world’s irrigated crops Drip irrigation (efficiency 90–95%) Above- or below-ground pipes or tubes deliver water to individual plant roots. Drip 90-95% Costly 1%

Solutions: Reducing Irrigation Water Waste Fig , p. 336

Less-Developed Countries Use ______- ________ Methods for Irrigation Human-powered treadle pumps ______ to build ______ power Treadle pump in Bangladesh Low Tech $25 leg

Less-Developed Countries ________________ harvesting and storage Uses pipes and channels to direct and store water Especially useful in areas that have a short _____________ season Create a polyculture ______________ over crops reduces ________________________ ___________________ fields to reduce water loss Rainwater monsoon canopy evaporation Mulch

We Can Cut Water Waste in Industry and Homes ________________ water in industry Fix ______________ in the plumbing systems Use water-thrifty landscaping: __________________ Use __________ water – water from bathtubs, showers, dishwashers, sinks To irrigate lawns, clean cars, etc. Pay-as-you-go water use…water _______________ Recycle leaks xeriscaping gray meter

Xeriscaping in Southern California Fig , p. 338

We Can Use Less Water to Remove Wastes Currently, we use large amounts of clean freshwater to ___________ away industrial, animal, and household wastes According to the FAO, within the next 40 years we will need the world’s ______________ flow of river water just to _______________ and _____________ the wastes we produce flush entire dilutetransport

We Can Use Less Water to Remove Wastes We could save much of this water by using systems that mimic how nature deals with waste… Chemical __________________ Example: human sewage contains valuable plant nutrients…use this to create a nutrient-rich _______________ to apply to croplands Ban the discharge of ________________ industrial chemicals into sewage treatment plants (chemical overload) Waterless composting toilets - composting ____________....use as soil fertilizer Recycling! sludge toxic chamber

Fig , p. 339 Solutions Sustainable Water Use  Waste less water and subsidize water conservation  Do not deplete aquifers  Preserve water quality  Protect forests, wetlands, mountain glaciers, watersheds, and other natural systems that  store and release water  Get agreements among regions and countries sharing surface water resources  Raise water prices  Slow population growth

What Can You Do? Water Use and Waste Fig , p. 339

13-7 How Can We Reduce the Threat of Flooding? Concept 13-7 We can lessen the threat of flooding by protecting more wetlands and natural vegetation in watersheds, and by not building in areas subject to frequent flooding.

Some Areas Get Too Much Water from Flooding (1) Some areas have too little water, but others sometimes have too much because of natural flooding… A flood happens when water in a stream overflows its normal channel and spills into an adjacent area, called a _____________________ Highly productive wetlands Provide natural flood and erosion control Maintain high water quality Recharge groundwater floodplain

Some Areas Get Too Much Water from Flooding (1) Many people live on floodplains to take advantage of their many assets, such as… ________________ soils Water for _________________ Nearby rivers for transportation and ______________ _______________ for urbanization and farming To reduce the threat of flooding, rivers have been… narrowed and straightened (__________________) Surrounded by protective ______________ and walls _______________ to create reservoirs fertile irrigation recreation Flat land channelized levees dammed

Some Areas Get Too Much Water from Flooding (2) Human activities make floods worse Levees can break or be ________________ Paving and development increase ______________ Removal of water-absorbing ________________ _______________ and building on wetlands that naturally absorb flood waters Rising sea levels from global warming means more coastal flooding overtopped runoff vegetation Draining

Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Tree roots stabilize soil Vegetation releases water slowly and reduces flooding Forested Hillside Agricultural land Stepped Art Tree plantation Roads destabilize hillsides Overgrazing accelerates soil erosion by water and wind Winds remove fragile topsoil Agricultural land is flooded and silted up Gullies and landslides Heavy rain erodes topsoil Silt from erosion fills rivers and reservoirs Rapid runoff causes flooding After Deforestation Evapotranspiration decreases Fig , p. 340 “To protect your rivers, protect your mountains.” Chinese proverb

Deforestation Above China’s Yangtze River Contribute to Erosion and Floods Fig , p : severe flooding in China’s Yangtze River Watershed Killed at least ______________ people Chinese officials banned tree cutting in the watershed and accelerated replanting 15 million

Case Study: Living Dangerously on Floodplains in Bangladesh Bangladesh: Dense population on coastal floodplain Depend on moderate floods maintain ___________ soil During flooding, families can take refuge on their _______ and use them as ________ if necessary Severe floods used to occur only every _____ years or so fertile roofs rafts 50

Case Study: Living Dangerously on Floodplains in Bangladesh ______________ frequency of large floods due to… development in the __________________ foothills Population growth Deforestation Overgrazing Unsustainable farming Destruction of coastal ______________: no longer protected from storm surges Increased Himalayan wetlands

Bangladesh is one of the few less-developed nations that is preparing for rising sea levels… Using crops that can __________________ flooding, saltwater, and drought better Building ponds that can help to _____________ monsoon rainwater Creating a network of earthen ___________________ that can help protect against high tides and storm surges tolerate collect embankments

Fig , p. 342 Solutions Reducing Flood Damage Preserve forests on watersheds Straighten and deepen streams (channelization) PreventionControl Preserve and restore wetlands in fl oodplains Tax development on fl oodplains Build levees or fl oodwalls along streams Use fl oodplains primarily for recharging aquifers, sustainable agriculture and forestry Build dams

Review Questions! Identify these types of irrigation. Flood Irrigation Drip Irrigation Center-Pivot (LEPA)

Review Questions! What are some ways that industries and housing can reduce water waste? What are some of the benefits of moderate flooding? Recycle used water (gray water) Fix leaks xeriscaping Use less water for diluting/transporting human waste Fertile soil Wetland habitats Maintains water quality Recharges ground water

Review Questions! What types of human activities are increasing the occurrence and risks of flooding? Draining or developing floodplains and wetland areas Removing vegetation Global warming – coastal flooding